Reciprocator for X-ray apparatus



. April 18, 195.0

R. H. MORGAN ETAL RECIPRocAToR FOR K RAY APPARATUS Filed May 5, 1946Patented Apr. 18, 1950 RECIPROCATOR FOR X-RAY APPARATUS Russell H.Morgan and Paul C. Hodges, Chicago, Ill., assignors to the United Statesof America as represented by the Secretary of War Application May 3,1946, Serial No. 666,903

This invention relates generally to a reciprocating apparatus for X-raygrids but more particularly to an apparatus of this type whichautomatically starts the energization of the X-ray tube corresponding toa predetermined location of the grid in its reciprocatory path.

One object of the invention is to provide combined means forreciprocating a grid and star*- ing the exposure of the X-ray filmimmediately after reversal in direction of the reciprocating grid.

Another object of the invention is to provide a reciprocating apparatusfor X-ray grids combined with automatic means for commencing theexcitation of the X-ray tube when the grid is in a position' to travelthe longest possible distance without reversal of direction.

These and other objects will be apparent from the following detaileddescription of the preferred embodiment of the invention taken inconnection with the accompanying drawings in which:

Figure l is a diagrammatic view showing the grid, the reciprocatingmechanism therefor, and the electrical circuit from the latter to theX-ray tube;V

Figure 2 is a partially sectionized elevational view showing thereciprocating mechanism; Y

Figure 3 is a sectional View taken on the .line 3--3 of Figure 2;

Figure 4 is a sectional view taken on the line 4--4 of Figure 2; and

Figure 5 is a top plan view of the reciprocator housing. f

Like reference characters are used to designate similar parts, in thedescription and in the drawings.

Briefly stated, this invention comprises a mechanism for reciprocatingan X-ray grid and for controlling the energization of the X-ray tube atpredetermined locations in the movement of said grid.

The portion of the apparatus foi` reciprocating the grid is similar tothat described in copending application Serial No. 495,690, led July 22,1943, now Patent #2,467,592. To this device has been added contactswitches which are operated by the reciprocating mechanism, the switchesbeing electrically connected to a relay for controlling the operation ofthe X-ray tube.

Referring to Figures 1 and 2, the numeral I0 indicates a base whichforms a support for a rcciprocator housing l I and an electric drivingmotor I2. `The motor I2 is supported by a resilient mounting I3 which isattached to a base I0. The

base I0 forms the bottom of the housing I I which 55 3 Claims. (Cl.Z50-62) includes side walls I4, I4', end walls I5, I5', and a Lucitecover plate I6 in which are mounted two ball catches I'I and I1connected by a metal strap I8. These ball catches function as contactsof the grid switch I9, as will be further described.

The resilient mounting I3 which supports the motor I2 is attached to thebase I. The driving shaft 2n of the motor I2 is connected through aflexible coupling 2I to the operating shaft 22 of the reciprocatingmechanism, said operating shaft being rotatably mounted within bearings23 and 24 in the end walls I5, I5' of the housing II. The operatingshaft 22 of the reciprocator is provided with left-hand and right-handthreaded portions 25 and 25. Thus a portion 25 of the shaft 22 isthreaded in one direction while a similar portion 25' is threaded in theopposite direction. The end walls I5 and I5' of the housing II aredrilled for the reception of a parallel guide rod 28 on which a forkedmember 29 reciprocates and oscillates. This member 23 comprises a forkedbody 30 drilled axially to receive the rod 28, on which it is slidablymounted, the forked body 30 being formed to provide two arms 32 and 33which extend toward the cover plate I6, one on either side of therotating shaft 22, as illustrated in Figure 2. The outer side portionsof the arms 32 and 33 are threaded so that they may removably engage thescrew threaded portions 25 and 25 of the shaft 22, and are set at suchan angle, relative to each other, that one of the arms may engage thethreaded portion 25 or 25 at a given time. At the extremity of arm 32 ismounted a switch member or trigger 52 formed of an angle support 53which is attached to the arm 3 2 and is provided with a contact member54. Extending outwardly from the body 30 of the forked member 29 is athird arm 34, in the end of which is a spring pressed detent 35 adaptedto ride smoothly over the rod 36 which is slidably mounted in `a bearingopening 3| within the bracket 51 and the bushing 2? located in the endwall I5'. Located in abutting relation on either side of the arm 34 andsecured to the rod 33 are the collars 31 and 38. It will thus be seenthat longitudinal motion of the forked member 29 imparts correspondinglongitudinal motion to the rod 3S. The rod 33 is mounted for slidingmovement within the bearing opening 3i located in bracket 51 and withinthe bushing 2'I located in the end of the housing I I. The inner end ofthe rod slidably projects into the drilled opening 62 in the end wall I5and the unconned end. of the rod proto an arm 39 (Figure 1), securelyfastened to the the threaded portion` of the shaft 22.

Potter-Bucky grid 40 which is reciprocated within a frame 55 beneath theX-ray tube 4I.

The angles at which the arms 32, 33 and 34 project from the body of theforked member 29 are such that when the detent 35 lies on one side ofthe rod 36 the threaded portion of the arm 32 engages the threadedportion 25 of the shaft 22; andwhendetent 35 lies on the other side ofthe rodthe threaded portion of the arm 33 engages the threaded portion25 of the shaft 22 as shown in Figure 2. Longitudinal motion is..

imparted to the forked member 29 by. virtueof the threaded engagementof' either of the arms 32 or 33 with the rotatingshaft: 22; thezdetent35 imparting a counterforce preventing the arm from disengaging itselffrom the rotating shaft 22.

On either end of the rotating shaft 22 arethe disc cams 42 and 43. Theperipheral surface of each of the said cams is circular except*` for onelobe as shown in Figure 2.

Two camfollowers @if and 45 are located in suchl azpositionvon-arins 32Aand 33, respectively, thatawhen the forked member 29, advancing toward;the cam 42 or the cam-43 by virtue of the rotationof thesh'aft`22,reachesieither one of the cams, the cam engages its respective camfollowen quickly disengages one threaded arm fromtheshaft` 22, snaps thedetent across the rod 33and engageswith the other threaded arm that: waspreviously disengaged.

Thus; theA reciprocating mechanism may be seen'to operate as follow-s:

The 'motor l2 `rotates the double-threaded shaft 'laat afconstant speed.When the threaded'portion-of the armY 32 isengaged with the threadedportion`2'5'ofl the-shaft 22, forked member 233s caused to travel in alongitudinal direction toward the cam 42. In so travelingv the forkedmemberslides over the rod 28' and by virtue of its connection to the rod33, through the arm 34 andthe collars 3'! and 38, causes the rod 35 totravelin a like direction. The rod 33 through itsi-connectionwith thearm 33, which is in turn connected-with a Bucky grid or diaphragm 4B,causes a longitudinal motion of the saidV grid which is slidably'mountedWithin the frame 55, When the arm 32 reaches the cam 42, the saidcamengages the cam follower 44 and instantaneously disengages the arm 32from the threadedportion- 25 of the shaft 22, snaps the detent 35 to theopposite side of rod 33 and in turn engages the threaded portion of thearm 33 with the threaded portion 25 of the shaft 22. The last-mentionedengagement produces almost instantaneous `reversal of the motion of theforked member ze and causes the said member to travel ln-aflongitudinaldirection ktoward the cam 43.

This reversal occurs in less than one-fourth ofoneper cent of the timeneeded for one complete grid cycle. The forked member 29, through itsconnection Withthe rod 36 andthe arm 33, causes Ia similar reversal oftravel of the Bucky diaphragm lll) When the arm 33 of the forked member2li-reaches the cam 43 the follower 45 engaged by the cam 43 whichcauses disengagement of the arm 33 from the threaded portion 25'and-reengagement of the armV 32 with This produces another reversal intravel and causes 'theforked member 29- to travel in its originaldirection. Thus, the forked member 29 and there- Vby:the,-l=!otter-Buckygrid 43 to which it is attached travel uniformly'in a to-and-frodirectlonrev ersal of travel being eiected bythe dis- .engagmentofone-of the armss32or 33 through the engagement of the respective cams 42or 43 with the respective cam followers 44 or 45 and the subsequentengagement of the opposite arm.

As the grid reverses and starts to move inwardly from its position shownin Figure l, the metal contact 54 of trigger 52 attached to theleft-hand thread half-nut, momentarily strikes the outer ballfcatch I1but passesA the inner catch Il' Withoutrtouching it.4 On lthe outwardtrip the metal contact 54 of trigger 52 strikes the inner ball catch I1but passes the outer one l1. By meansr of the grid switch I9 whichincludes the ball catches I1, l1 and trigger 52, and a self-holdingArelay/5,8 (Figure 1), exposures shorter: than 0.6secondv may be madewithout grid reversal, whereas1 longer exposures continue through one orseveral reversals of the grid. The relay is connected so that one sideof its coil 59 whichis grounded to housing Il receives ground from thegrid switch I9 and the other side receivesv volty A.. C. whentheexposure switch 53 is closed. After the exposure switch has beenclosed there isa momentary delay until the grid begins to travel inanew. direction and a pulse of ground comes from the grid switch, A pairof normally openrelay contacts 6l providesva self-holding circuit sothat once the relay has closed it remains closedy as long as theexposure switch is held dow-n as there is a continuous flow of currentthrough the coil 59 of therelay 58.

From a consideration ofv ther embodiment of this invention, it will beappreciated that asimple and eifective means has been provided forreciprocating a Potter-Bucky gridor diaphragm at the speed required toavoid shadowsthereof appearing on the radiograph. Positive drive in bothdirections and reversal well within the limited permissible timev areinsured by the cam means employed'toreverse the travel in eitherdirection, and automatic energization of the X- ray tube lseifectedafter areversal of the grid to avoid beginning an exposureV periodwhen'the grid is either in a position where it is motionless at the endof a reciprocatory movement, or approaching such al position.

It will be apparent to those skilled in the art that various changes andmodifications can be made in the apparatus of the disclosed inventionwithout departing from the spirit and scope thereof as defined in theappended claims.

Havingthus-descr-ibed our invention, what we claim as new and wish tosecure by Letters Patent-is:

1. A mechanism for reciprocating a Bucky grid of an X-ray apparatusincluding an X-ray tube and circuitmeans for energizing the` tube, thecombination which comprises mounting means for" a screw, arotatable-screw mounted in the mounting means, thescrew havingoppositely directed threads along successive portions of its length, anactuating member mounted on the screw and having a pair of arms disposedon opposite. sides of thescrew, onevof the said arms being inYengagement with the screw for effecting lineal movement of the actuatingmember in one direction, means operating on the actuating member-at theend of travel of the actuating member in one direction foreifecting atilting motion of the'member for disengaging the said arm of theYactuating member from the screw and engaging the-other arm of the memberwith the oppositely directed threads of the screw'for effectingreverse,l travel of the actuating member, means. for continuously.-rotating the screw, reciprocatory means connected to the grid and theactuating member for reciprocating the grid responsively toreciprocation of the actuating member, and means engageable by each armof the actuating member at the end of each reciprocation and within saidX-ray tube circuit constituting a grid switch, said circuit alsoincluding a manually operated exposure switch, and a relay switchadapted to control the energization circuit eiecting the operation ofthe X- ray tube, said relay switch being adapted to effect initialenergization of the X-ray tube through the operation oi the grid switchafter reversal of the reciprocating mechanism and to effect theuninterrupted energization of the X- ray tube regardless of theoperation of the grid switch with the movement of said arms, until thetermination of the energization, by the operation of the exposureswitch, at the conclusion of the exposure.

2. A mechanism for reciprocating a Bucky grid of an X-ray apparatusincluding an X-ray tube and circuit means for energizing the tube, thecombination which comprises mounting means for a screw, a rotatablescrew mounted in the mounting means, the screw having oppositelydirected threads along successive portions of its length, an actuatingmember mounted on the screw and having a pair of arms disposed onopposite sides of the screw, one of the said arms being in engagementwith the screw, rotation of the screw effective lineal movement of theactuating member rst in one direction and then in reverse directionthrough the oppositely directed threads, means operating on the memberacting at the end of travel of the actuating member for effecting atilting motion of the member for disengaging the said arm of theactuating member from the screw and engaging the other Y arm of themember with the oppositely directed threads of the screw for eiectingreverse travel of the actuating member, means for continuously rotatingthe screw, reciprocatory means connected to the grid and the actuatingmember for reciprocating the grid responsively to reciprocation of theactuating member, and means within said X-ray tube circuit including agrid switch operated by the movement of said arms, a manually operatedexposure switch and a relay switch adapted to control the energizationcircuit effecting the operation of the X-ray tube, said relay switchbeing adapted to eiect initial energization of the X-ray tube throughthe operation vofthe grid switch after reversal of the reciprocating"vmechanism and to effect the uninterrupted energization of the X-ray tuberegardless of the operation of the grid switch with the movement of saidarms, until the termination of the energlzation by the operation of theexposure switch at the conclusion of the exposure.

3. An apparatus for reciprocating a Bucky grid of an X-ray apparatusincluding an X-ray tube and circuit means provided with an exposureswitch and a relay switch, and adapted for energizing the tube, thecombination which comprises a housing mounting means for a screw withinsaid housing, a rotatable screw mounted in the mounting means, the screwhaving oppositely directed threads along successive portions of itslength, an actuating member mounted on the screw and having a pair ofarms disposed on opposite sides of the screw, the said arms beingthreaded oppositely to each other to correspond to the opposite threadson the screw, one of said arms being in engagement with the screw foreffecting lineal movement of the actuating member in one direction, cammembers mounted on the screw and rotatable therewith adapted to beengaged by the actuating means after a predetermined distance of travelthereof along the screw for tilting the actuating member and therebydisengaging the said arm of the actuating member from the screw andengaging the other arm of the member with the oppositely directedthreads of the screw for eiecting reverse travel of the actuatingmember, means for continuously rotating the screw, and reciprocatingmeans connected to the grid and the actuating member for reciprocatingthe grid responsively to reciprocation of the actuating member, a pairof spaced contacts in the housing adapted to energize the circuit means,and a contact on the rst mentioned arm of the actuating member adaptedto clear one of the spaced contacts in the housing on outward movementof the actuating member along the screw and to engage momentarily theother of the spaced contact members responsively to the actuating memberreaching its end of outward travel along the screw and responsively totilting motion of the actuating member by the cam means, the contactmember in the housing missed by the contact on the said arm on theoutward movement of the actuating member being engaged by the contact onthe arm as the arm of the actuating member is tilted by the cam meansfor initiation of the outward movement of the actuating member, wherebythe X- ray tube included in said circuit means is energized immediatelyafter a reversal of said grid in its reciprocating paths and theenergizing circuit kept closed by the relay switch until the exposureswitch is opened.

RUSSELL H. MORGAN. PAUL C. HODGES.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,387,598 Folberth Aug. 16, 19211,471,081 Waite Oct. 16, 1923 2,062,562 Dent Dec. 1, 1936 2,138,555Otvos Nov. 29, 1938 2,204,347 Files June 11, 1940

